Im not sure if this will work, but the way i see it, theres only one thing to do:
get some kind of adapter that works (canon to c or whatever mounts), and if this does not excist, you have to make one yourself. once you get a hold of one of these, you have to split it in two, and mount a tube (material not important, but inside must be non reflective) with the lenght equivalent of the difference between the two register distances (40mm - 17.5mm) and simply glue both halfs on each end of the tube, then it should be fixed?
but really, i dont know about how to fokus and so on, i just came to think of it
sorry for the long and difficult explanation